1. Field of the Invention
The invention generally relates to an envelope/bag used for confidential materials and in particular relates to an envelope/bag that leaves visible evidence when being opened.
2. Related Art
Conventional mails in the past several centuries have played an important role in communicating and expressing one's feelings and emotions (not to mention what one can put in the mail). In order to ensure privacy, various types of envelopes and bags were developed to contain such information.
As “privacy” tends to draw unwanted curiosity, in order to easily detect whether contents inside the envelope or bag has been tampered, sealing methods from ancient wax seals to today's super bond glue and tapes were developed. Still, after all these years no matter how hard people tried, simple tampering methods continue to violate privacy and leave envelopes or bags visually intact. Nowadays, in accompany with new technologies and worldwide web developments, electronic mails have become an important communication media among people. However, most consumers think that electronic mails are virtual, insubstantial and intangible, and may have safety problems during transfer. Therefore, conventional mails are still commonly used to deliver formal or important articles or items. To secure the safety and confidentiality of the mail becomes an important issue to be resolved.
It is well known that sometimes in the military, an officer can check a private mail by simply cutting a narrow slit on any side of the envelope to access the content, then gluing it back afterwards. Yet, the recipients will not notice the breakage.
Other conventional safety mails, such as express envelopes for delivering confidential documents, bank and credit card statements, credit cards or other important articles, face the same serious problem related to privacy and security.
For example, as shown in FIG. 6a, after an express envelope 70 is cut at its edge and forms a slit 71, items inside the envelope can be easily peeped or stolen from the slit edge; then, as shown in FIG. 6b, after the slit is recovered by re-seal or glue, not only will the envelope seem like it's never been opened, it will also be hard for the recipient to notice the breakage.
FIG. 7 shows a convention confidential envelope 80 having a tearing line 83 at the sealed side. Normally, breakage of the tearing line is a sign of being “already opened”. However, an intruder can access the enclosure of the envelope from other portions, such as by cutting a slid 82 at the edge of the envelope 80; then glue it back easily afterwards without any sign or evidence for the recipient to notice. Other similar stealing or intrusion manners can also happen, and that make most currently used confidential envelopes meaningless and useless.
Therefore, it is required to have a confidential envelope that clearly shows evidence after being opened.
Japan publication number 61-110547 disclosed an envelope characterized in: using a strong coating paint to print texts, graphics and symbols onto any two opposite sides of the inner film (2a), forming the envelope and sealing the envelope by this printed side. In other words, before the envelope is sealed, a layer of printed texts, graphics or symbols is painted on its “inner surface”. Since this printed layer is hidden in between the two sides of the envelope being sealed, it cannot be seem from outside when looking at the envelope. However, if the sealed area is peeled apart, the hidden printed layer will reveal and the printed texts, graphics or symbols will be separated as shown in FIG. 8.